Stress is thought most often to be a major player in emotional health, possibly affecting your psyche, but rarely your physiological health and fitness. I would argue that this is an oversight. Like sleep deprivation, stress can have serious effects on your health in many of the same areas. Due mainly to a constant level of cortisol (our primary stress hormone), over-stressed people are more likely to suffer from anxiety, depression, digestive problems, heart disease, sleep problems, weight gain, and memory and concentration impairment. Sounds pretty bad for an otherwise healthy person, huh?